Provided are hydrophilic substrates provided with a hydrophilic polymer layer having controlled surface uniformity and irregularities, and methods for preparing the hydrophilic substrates. Included are hydrophilic substrates including a substrate having a surface containing at least one group represented by —N(R.sup.1).sub.2 or —N(R.sup.2).sub.3.sup.+ wherein each R.sup.1 or R.sup.2 is the same or different and represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group optionally containing a hetero atom; and a hydrophilic polymer layer provided on the surface of the substrate.

An embolization system and methods for controlling solidification of embolic compositions comprising a first and a second embolic component that react with each other in vivo at a target site to form an embolic material, with the embolic components being dilutable in physiological fluids so that they do not form an embolic composition at a site that is not desired.

An embolization system and methods for controlling solidification of embolic compositions comprising a first and a second embolic component that react with each other in vivo at a target site to form an embolic material, with the embolic components being dilutable in physiological fluids so that they do not form an embolic composition at a site that is not desired.

[Problem to be Solved] To Provide a method for producing an acid-decomposable polymer having a reduced metal ion content, which suppresses decomposition and deprotection of the acid-decomposable polymer. [Means to Solve the Problem] The method for producing an acid-decomposable polymer according to the present invention comprises the steps of: preparing a polymer solution comprising an acid-decomposable polymer; washing an acidic cation exchanger with an organic solvent until the water content in the organic solvent discharged from the acidic cation exchanger falls to 400 ppm or less; and passing the polymer solution through the washed acidic cation exchanger to reduce the metal ion content of the polymer.

A pattern forming material according to an embodiment is a pattern forming material comprising a polymer composed of a plurality of monomer units bonded to each other. Each of the monomer units includes an ester structure having a first carbonyl group and at least one second carbonyl group bonded to the ester structure. A second carbonyl group farthest from a main chain of the polymer constituting the pattern forming material among second carbonyl groups is in a linear chain state.

A pattern forming material according to an embodiment is a pattern forming material comprising a polymer composed of a plurality of monomer units bonded to each other. Each of the monomer units includes an ester structure having a first carbonyl group and at least one second carbonyl group bonded to the ester structure. A second carbonyl group farthest from a main chain of the polymer constituting the pattern forming material among second carbonyl groups is in a linear chain state.

Particles for cell adhesion to be used for adhering highly adhesive cells present in an aqueous solution, said cell-adhesive particle comprising, in at least a part of the surface thereof, a wettable composition having an intermediate water content in the water-saturated state of 1-30 wt %.

Particles for cell adhesion to be used for adhering highly adhesive cells present in an aqueous solution, said cell-adhesive particle comprising, in at least a part of the surface thereof, a wettable composition having an intermediate water content in the water-saturated state of 1-30 wt %.

A composition contains ethylenically unsaturated quaternary ammonium cations with acetate counterions, where each of the ethylenically unsaturated ammonium cations contain only one non-aromatic carbon-carbon double bond and the composition contains less than one mole-percent chloride relative to quaternary ammonium cations can be polymerized to form a cationic polymer acetate.

A composition contains ethylenically unsaturated quaternary ammonium cations with acetate counterions, where each of the ethylenically unsaturated ammonium cations contain only one non-aromatic carbon-carbon double bond and the composition contains less than one mole-percent chloride relative to quaternary ammonium cations can be polymerized to form a cationic polymer acetate.